The New York Yankees finally found a reason for Anthony Rizzo's struggles the past two months. The team placed Rizzo on the injured list on Thursday due to a concussion he might've sustained at the end of May.

Yankees manager Aaron Boone said Rizzo complained about being "foggy" in recent days, prompting the team to send him for additional testing. Those tests showed "some cognitive impairment," leading to Rizzo's stint on the IL.

Rizzo might've sustained the injury in late May, when he collided with San Diego Padres outfielder Fernando Tatis Jr. on a pick-off play at first base. The collision occurred in the sixth inning of the Yankees' May 28 game against the Padres.

Following a strikeout, Yankees catcher Kyle Higashioka fired the ball to first base, hoping to catch Tatis too far off the bag. Rizzo made the catch and tagged Tatis, ending the inning. After the play, however, Rizzo stumbled away and went down on one knee on the infield dirt.

Replays showed Rizzo's head bouncing off Tatis' leg as he tried to get back to the bag.

Boone said MLB put Rizzo through concussion tests shortly after the play, and those tests came back clean. Rizzo was not placed on the IL at the time and returned to action June 2. In 46 games since the collision, he has hit just .172/.271/.225 in 192 plate appearances. Prior to the injury, he was in the midst of a resurgent year, batting .304/.376/.505.

Rizzo was asked about the injury Thursday and painted a pretty harrowing scene. He said there were days when he would wake up feeling hungover, and he admitted there were times when he forgot how many outs had been recorded during an inning.

Rizzo said he informed the team about some of those symptoms after the series against the Baltimore Orioles in late July. Despite that, Rizzo was in the lineup for the next two games against the Tampa Bay Rays.